Imaging system for a medical diagnostic apparatus

ABSTRACT

A medical diagnostic apparatus has a computer, a bus, processors, memories and an input arrangement, the imput arrangement including an adjustment arrangement for the nearly simultaneous adjustment of at least two input parameters, to which a processor is allocated for conversion into control parameters.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic resonance system of the typehaving an imaging computer, an image acquisition unit, a controlarrangement including a computer, a bus, processors and memories, andhaving an input arrangement for the manual entry of sequence parameters.

2. Description of the Prior Art

In conventional examinations, e.g. in magnetic resonance (MR), beforethe measurement a control sequence, e.g. spin echo or turbo spin echo,is selected, and is modified by entering user parameters (UIPar=UserInterface Parameter). In MR technology, user parameters (UIPar) of thissort can be the repetition time TR, the echo times TE or TE(i), thenumber of slices, the slice thicknesses, the matrix size, the imagesegment FOV (Field of View), the slice position, the slice rotation, theflip angle, and the saturation slices.

From the sequence and the UI parameters, data sets and/or programs arecalculated that are loaded into the control hardware and are interpretedthere. The control hardware basically is formed by the gradientgenerator, the RF generator and the data recording.

At the end of the measurement, or accompanying the measurement, the rawdata are evaluated, or during the imaging magnetic resonance (MRI)images of arbitrarily rotated slices through the subject of examinationare calculated. If modifications are desired, the UI parameters mustsubsequently be re-entered, and the sequence begins again.

The entry of the parameters has previously taken place on the displayscreen via an input mask in which there are provided fields foralphanumeric text or numbers, fields to be marked with a cross, orslides, on which an analog input is possible with the aid of a mouse.

Given a graphical slice positioning, the user selects a slice and movesit in parallel fashion or rotates it by setting the cursor to what arecalled angle points, and these are then moved.

This sort of input is inconvenient, especially if inputs are made duringmeasurement and their effects are supposed to be observedquasi-simultaneously with the input. It is then not realistic to expectthat a display screen mask and the MR images can be observed at the sametime. Moreover, it is very inconvenient to place the cursor precisely onan input field, or even an angle point, using the mouse.

In U.S. Pat. No. 5,144,242, a microcoded pulse sequencer for real-timecontrolling of an MR system is specified in which microcommands from onememory region are loaded into another region.

U.S. Pat. No. 5,349,296 relates to an MR apparatus that is controlled bya workstation. For the reproduction of an image reconstructed from themagnetic resonance data, a scan processor is provided that controls thescan parameters and the reconstruction processor. A scan sequencercontains a master board for microcode, which controls the scan processordependent on the commands of the scan processor. A number of codesdescribing the gradients and the RF pulse form is read into a memory.Dependent on a clock rate, the data are read into corresponding outputregisters step-by-step.

From the journal “Magnetic Resonance Imaging,” vol. 9 (1991), pages627-634, an apparatus is known that can be used as an MR pulseprogrammer. It produces a microcode in the shortest time and transmitsthese data.

SUMMARY OF THE INVENTION

An object of the present invention is to provide of creating an imagingsystem of the type described above that enables a simple and rapidchange between the various parameters, as well as a simple and rapidentry of the parameters. The above object is achieved in accordance withthe principles of the present invention in a magnetic resonance systemhaving an image computer, an image acquisition unit, a controlarrangement including a control computer, a bus and processors andmemories, and an imput arrangement for manually entering sequenceparameters, the imput arrangement including an adjustment arrangementwhich allows sequence parameters to be directly modified online duringan examination sequence. By means of this online MR sequencemodification, the measurement sequence and the evaluation can becontrolled simply and rapidly using the adjustment arrangement, e.g. inMR experiments for imaging, spectroscopy and interventional MR, sincethe modifications are transferred directly into the control procedure orprogram which is being executed.

It has proven advantageous for the input arrangement to be fashioned isin such a way that the modifications are routed directly to the controlapparatus.

A rapid entry of several values is achieved if the input arrangementincludes an adjustment means for the nearly simultaneous modification ofat least two parameters. In this way, the measurement sequence and theevaluation can be controlled by a joystick, which supplies two or threevalues from a value range simultaneously or nearly simultaneously.

According to the invention, the adjustment arrangement can modify theuser parameters, whereby a processor can be allocated to them for theconversion of input parameters into control parameters.

The input of the parameters can be still further simplified andaccelerated if the control arrangement includes a dual buffer in whichat least parts of new data are read in during a sequence that are usedduring a synchronous point of a sequence for controlling. A synchronouspoint can for example be the end of a sequence, of an individualmeasurement, or a manual stop command.

It has proven advantageous for a part of the control parameters to beloaded into the dual buffer in combined form in parameter blocks, whichare activated at the end of the sequence.

According to the invention, the dual buffer can be a buffer memory, orits function can be implemented as software.

A particularly simple input of the parameters results if the controlarrangement is formed by a joystick, a mouse or a trackball.

The user parameters can advantageously be modified by the is adjustmentarrangement if they relay the entered values to a processor thatconverts the values into user parameters.

In a magnetic resonance system for the production of images ofarbitrarily rotated slices through a subject of examination, such userparameters can, according to the invention, be for example a rotation ofthe slice about two axes, a displacement of the slice, a two-dimensionalmodification of the image segment and/or a modification of the matrixsize.

According to the invention, the adjustment arrangement can also be usedfor image manipulation by using them to control the windowing, wherebyfor example the center of a window can be selected in an imagebrightness axis, and the amplitude window can be selected symmetricallyabout this center.

DESCRIPTION OF THE DRAWINGS

The single FIGURE is a schematic block diagram of a medical diagnosticapparatus constructed and operating in accordance with the principles ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the FIGURE, a part of a medical diagnostic apparatus is shown, e.g.an MR installation specified on pages 479ff. of the book “BildgebendeSysteme für die medizinische Diagnostik,” by Erich Krestel, comprising acontrol arrangement and an imaging system with a control computer 1. Agradient processor 6, an RF processor 7 and a data acquisition unit 8are connected to the control computer 1 via a data bus 2 and memories 3to 5. These are in turn connected in a known way with the gradientgenerators, RF generators, and data recorders (not shown).

Furthermore, an image computer 9 is connected to the data bus 2connected to the control computer 1, said image computer 9 beingconnected to a monitor 10 for the representation of a diagnostic image.

An input arrangement 11 is connected with the control computer 1 and animage computer 9 via the data bus 2, for the entry of user parametersor, UI parameters and image manipulations via a processor 15. The inputarrangement 11 can, for example be formed by, one or more of a joystick12, a mouse 13 and/or a pushbutton or switch 14.

It is essential for the input that two values can be modifiedsimultaneously or quasi-simultaneously. If the joystick 12 is of thetype that can be pushed in or pulled out, three values can be modifiedat the same time. In place of a joystick 12, a mouse 13, a trackball, anacoustic (ultrasound) locator, an optical locator, or similar locatorscan be used.

According to the table bellow, some conversions between UI parametersand control parameters are required. For this purpose, the processor 15is allocated to the joystick 12, the processor 15 containing, in aparameter memory 16, the programs for conversion and checking of thetolerances within which a parameter is permitted to change. A change inone of the parameters can have an influence on the limits of anotherparameter. The maximum displacements of the joystick 12 always representthe tolerance limits.

If the control computer 1 for the loading of the control arrangement issufficiently fast, it can be used in multitasking operation as ajoystick processor.

In the following, four alternatives are indicated for the way in whichthe control parameters according to the table can be loaded into thecontrol arrangement during the measurement.

During the measurement, a complete new data set and/or programs areloaded into a dual buffer realized by means of software. At the normalend of a sequence, or at an end of a sequence forced by a stop command,a change over into the other buffer memory takes place, and the sequencewith the new parameters starts automatically. For this purpose, thesequence start and the loading of the buffer memory must besynchronized. This method with a dual buffer permits not onlymodifications of the UI parameters but even a change of the sequencetype, but however is dependent on a rapid loading mechanism.

A software dual buffer can pose runtime problems if one of the memories3 to 5, called the “dual port memories,” is accessed simultaneously bythe loading processor and the control processor, and wait cycles thusarise for the control computer 1. If the dual buffers are realized inhardware, e.g. as buffer memories 17 in the processor 15, no wait cyclesresult.

Normally, during a measurement only a few UI parameters, and thuscontrol parameters, change. It is then not required to load an entiresequence. It is entirely sufficient to combine a few control parametersin parameter blocks and load them. At the end of the sequence, the newparameter blocks are then activated.

The activation can take place by means of the conversion of pointers orby copying the parameter blocks loaded during the sequence, whilemaintaining all pointers.

This method presupposes that control values that change due to UIparameters according to the table are not reflected in the programand/or data set as constants, but rather that at these locations thereare pointers to one or more parameter blocks. A modification of UIparameters then has the effect of a conversion of the UI parameters intocontrol parameter blocks, which are then transmitted.

As a final possibility, modified control parameters can however also beloaded directly without synchronization. It is true that some images orresults are then unusable. This is not a disturbance, however, if theimage calculation times are small enough. This method is the fastest ofall the methods discussed here to fore.

However, it must be ensured that raw data and/or images that are storedare not based on sequences with incomplete new parameters. This can beachieved by receiving the store command only at the end of the sequence,and restarting the sequence with the parameters last inputted. After thestore command, no more modifications of the UI parameters may beaccepted.

According to the invention, the adjustment arrangement can also be usedfor image manipulation by using them to control the windowing, wherebyfor example the center of a window can be selected in an imagebrightness axis, and the amplitude window can be selected symmetricallyabout this center.

By means of the possibility of simultaneous modification of two or threevalues, this input arrangement 11 is suited for various inputs.

By pushbuttons or switches 14, housed either on the joystick 12 or in aseparate housing, the evaluation of the input data can be modified.

In this way, various inputs can be modified by the joystick 12. Forexample, the angle of rotation of a slice about two axes can be set. Bypushing in or pulling out the joystick 12, a forward or rearwarddisplacement can be achieved at the same time.

A slice can also be moved horizontally and vertically. The forward orrearward movement can take place by pushing in or pulling out thejoystick 12. If this is not possible, a changeover to forward andrearward can take place via the buttons or switches 14.

The image segment (FOV) can be enlarged or reduced in two dimensionsaccording to the invention. By pushing in or pulling out, it is inturnpossible simultaneously to carry out a forward or rearwarddisplacement. A selection of the matrix size can also take place.

By means of the pushbuttons or switches 14, a changeover toone-dimensional input can also take place. The most important parameterof this sort is the repetition time TR. Likewise, the modification ofone-dimensional values can be achieved by means of longer or shorterpushing of a button.

By button pressure or switch, the joystick 12 can also be used in imagemanipulation, e.g. in windowing. In order to select a window, a centeris marked in an image brightness axis and an amplitude window is enteredsymmetrically about this center. For an asymmetrical window, asymmetrical window is first selected and a new center is determined.

According to the invention, the input arrangement 11 can also beconnected to the control computer 1 directly via the data bus 2. Anadditional direct connection of the input arrangement 11 with the imagecomputer 9 would also be possible.

A processor for faster conversion of the input data into user parameterscan be allocated to the input arrangement 11. It can be provided eitherin the control computer 1, the image computer 9, in the inputarrangement 11 itself or between the input arrangement 11 and the databus 2.

By means of the inventive construction of the imaging system, oneobtains an apparatus with which a rapid method can be realized forcontrolling the measurement sequence and the evaluation, e.g. in MRexperiments for imaging, spectroscopy and interventional MR, by means ofthe joystick 12 or other apparatuses that supply two or three valuesfrom a value range. By means of the inventive construction of the inputarrangement 11, two values can be modified simultaneously orquasi-simultaneously. If the joystick 12 also has the possibility ofbeing pushed in or pulled out, three values can simultaneously bemodified and entered.

In the inventive online MR sequence modification, modifications arebrought directly into the control procedure or program currently beingexecuted without the necessity of re-calculating the sequence controldata or programs for each modification, so that MP sequences can bemodified during the measurement.

The online input is important for diagnosis, and in particular for“interventional MR imaging.” In “interventional MR imaging,” operationsin the brain, among others, can be carried out under MR observation. Ajoystick 12 does not have to be employed as the input arrangement 11 forthese types of interventional procedures. Thus, for example, aninstrument manipulator can supply the locus information concerning howfar a tool, e.g. an injection needle, laser or surgical instrument, hasbeen advanced, automatically or controlled by the surgeon. For manuallyguided tools, the locus coordinate sensor, e.g. an ultrasoundtransmitter or light-emitting diodes, can be located in the tool. Forwork using a manipulator, it must be possible to give the manipulatorcommands such as stop, start, slow, fast. However, it must also bepossible to influence the MR sequence, so that as far as possible slicesthat are determined by the locus coordinates are shown in real time.Parallel to this, for example joystick inputs can modify the MR sequenceas the slice orientation.

Parallel to the production of the sequence control data or sequencecontrol programs, programs for the control computer 1 are generated sothat it can carry out, online and in a purposive manner, small changesof the sequence control data or programs directly in the controlling.

TABLE UI parameters Control parameters Repetition and echo times TR,Number of passes TI, TF Image segment FOV (Field of Number of passesView) Read and phase gradients, frequency offset Slice thickness Slicegradients, frequency offset Phases Matrix size Number of passesGradients, Frequency offset Phases Slice position Frequency offsetPhases Slice rotation Rotation matrix Saturation slices Frequency offsetPhases Jumps Number of passes Scale values (0 or #0) Automatic switchoffSequence stop effects ramp down gradients

Although modifications and changes may be suggested by those skilled inthe art, it is the intention of the inventor to embody within the patentwarranted hereon all changes and modifications as reasonably andproperly come within the scope of his contribution to the art.

What is claimed is:
 1. A medical imaging system comprising: dataacquisition means for acquiring magnetic resonance image data; an imagecomputer connected to said data acquisition means for constructing amagnetic resonance image from said image data; a control computerconnected to said image Computer and to said data acquisition means viaa bus for controlling acquisition of said image data and generation ofsaid image during a sequence execution having sequence parametersassociated therewith; and manually operable input means, having amanually operable input unit selected from the group consisting of ajoystick, a trackball and a mouse, connected to said bus for supplyingat least some of said sequence parameters to said control computer, andsaid input means including a processor connected to said manuallyoperable input unit, said processor being configured to respond to saidsequence parameters from said manually operable input unit to directlymodify at least some of said sequence parameters online during saidsequence execution.
 2. A medical imaging system as claimed in claim 1wherein said input means comprises means for directly feedingmodifications of at least some of said sequence parameters to saidcontrol computer.
 3. A medical imaging system as claimed in claim 1wherein said adjustment means comprises means for allowing substantiallysimultaneous modification of at least two values of at least some ofsaid sequence parameters.
 4. A medical imaging system as claimed inclaim 1 wherein said sequence parameters include user parameters, andwherein said adjustment means comprises means for modifying said userparameters during said sequence.
 5. A medical imaging system as claimedin claim 1 wherein said control computer employs control parameters forcontrolling acquisition of said image data and generation of said image,and wherein said adjustment comprises means for producing inputparameters corresponding to modifications of at least some of saidsequence parameters, and wherein said input means includes processormeans for converting said input parameters into said control parameters.6. A medical imaging system as claimed in claim 1 further comprising adual buffer, in communication with said control computer, in which atleast parts of new data acquired by said image acquisition unit areentered during acquisition of said image data, and wherein said controlcomputer comprises means for employing said new data for controllingacquisition of said image data and generation of said image.
 7. Amedical imaging system as claimed in claim 6 wherein said controlcomputer parameters for controlling acquisition of said image data andgeneration of said image, said control parameters being loaded into saiddual buffer as parameter blocks, which are activated at an end of saidsequence.
 8. A medical imaging system as claimed in claim 6 wherein saiddual buffer comprises a buffer memory.
 9. A medical imaging system asclaimed in claim 6 wherein said dual buffer comprises software means forentering said new data.
 10. A medical imaging system as claimed in claim1 wherein said adjustment means comprises means for supplying at leasttwo values from a value range to said control computer.
 11. A medicalimaging system as claimed in claim 1 wherein said adjustment meanscomprises means for producing input values, and wherein said input meansfurther comprises processor means for converting said input values intouser parameters.
 12. A medical imaging system as claimed in claim 1wherein said sequence includes selection of a slice angle, and whereinsaid adjustment means comprises means for modifying said slice anglerelative to two axes.
 13. A medical imaging system as claimed in claim 1wherein said sequence includes selection of a slice, and wherein saidadjustment means comprises means for displacing said slice.
 14. Amedical imaging system as claimed in claim 1 wherein said sequenceincludes obtaining image data from a multi-dimensional image segment,and wherein said adjustment means comprises means for modifying saidimage segment two-dimensionally.
 15. A medical imaging system as claimedin claim 1 wherein said sequence includes storing said image data in adata matrix, and wherein said adjustment means comprise means formodifying a size of said image matrix.
 16. A medical imaging system asclaimed in claim 1 wherein said adjustment means comprises means formanipulating said image.
 17. A medical imaging system as claimed inclaim 16 wherein said adjustment means comprises means for controllingwindowing of said image.
 18. A medical imaging system as claimed inclaim 16 wherein said adjustment means comprise means for selecting acenter of an image window along an image brightness axis and forselecting an amplitude window symmetrically around said center.